Switch



0t.26,1'94s. -G, H, BERKHOLDER 2,452,425

SWITCH Filed Jan. 5, 1946 Patented occ. ze, 194sv SWITCH George l-li. Berkholder, Minneapolis, Minn., as-

signor to Minneapolis-Honeywell Regulator- Company, Minneapolis, Minn., a corporation of Delaware Application January 5, 1946, Serial No. 639,334

-6 Claims. i

My invention relatesfto an improvement in snap switches of the magnetic type, and means by which an actuating force is applied to effect snap action of the contacts; and particularly relates to snap switches of the sensitive type adapted to be actuated by means moved gradually in response to change in a condition, s uch as temperature or pressure.

An object of this invention is to provide a switch of the character described which is capable of handling relatively heavy loads.

A more specific object is to provide, in a switch of the `class described, a novel arrangement of parts whereby the contacts upon initial engagement are firmly held in that condition and vibration between them is substantially eliminated.

A further object of this invention is to pro-vide a switch blade having a relatively small amplitude of movement which dampens or otherwise redu-ces bouncing between the contacts of a snap switch.

A still further object is to provide a switch blade with an internalbias which force aids in substantially eliminating bounce of the contacts of the snap switch.

Another object is to provide a new and improved switch in which bouncing or relative vibratory action between the contacts following initial closingof the switch is minimized to aid in avoiding fusing of the contacts.

It is yet another object of my invention to provide a snap switch with fewer parts than the devices of the prior art and at the Sametime accomplish better results in the present snap switch than the results which have heretofore been obtained. A

Other and further objects and advantages of my invention will be found in the description, the drawing, and the appended claims.

For a complete understanding of the invention, reference may be had to the following detailed description and accompanying drawing, wherein:

Figure 1 is a sectional view in elevation of theimproved snap switch;

Figure 2 is a top plan of the snap switch, the cover removed;

Figure 3 is a detailed view showing the improved switch blades employed in the snapswitch.

Figure 4 shows the switchv blade in unstressed condition.

The snap switch I is shown mounted in a casing Ill which comprises a base portion I2 and a. removable cover portion I4. The removable cover portion I4 has an aperture I6 receiving a reciprocating button I8 having an enlarged head .portion 20 spaced insidethe casing II.

A U-shaped bracket 22 is secured by a screw 28 to a terminal 26 in the base I2 of the switch housing II.

. provided in the form of an armature 28 having a cut-out portion 30 in its outer end to accomodate a contact. The armature 28 is formed with upturned flanges 32-32 on its opposed sides adjacent its inner end. The armature 28 is also provided with a substantially right angular extension. 33 at its inner end and having a substantially horizontal flange portion 34 extending from the right angular extension 32. A pin 36 extends through apertures in the arms of the U- shaped bracket 22 and the pin 86 also extends through apertures in the upstanding lugs 32-82.

of the armature 28 for pivotally mounting the armature 28 on the pin 36. A resilient arm 38 is secured by appropriate means to the flange 3i of the armature 28 which is provided with a raised portion il!! forcooperating with the reciprocating button I8. A contact 29 is secured to the armature 28. There is an electrical conductor i2 connecting the armature 28 with the' terminal 26. A biasingspring M is connected in an aperture in flange Stof the armature 28 and its outer end is secured to anchoring means in the base'of the housing II.

There is a terminal 66 mounted in the base I2 of the housing II which has an integral flat portion 48 extending inside the switch housing I I. contact 50 is mounted in the flat portion i8 of the terminal i6. A permanent magnet 41 is mounted adjacent the contact 50. A second contact 52 mounted in the flat portion i8 of the terminal 86 is adapted to engage the contact 29 onthe armature 28. The contact 52 is provided with a shank portion 55 which is externally threaded for cooperating with screw threads in an aperture in the terminal `i6. Contact 52 may be adjusted to determine the spacing between the armature 28 and the magnet lll when the contacts are closed and so provide the desired operating differential of the switch. A screw 5i is adapted for maintaining the adjustable contact .52 in its adjusted positions. i

A switchblade 56 offresilient spring metal is secured to a raised portion of the armature 28 at 58. 'I'he blade is shown in unstressed condition in Figure 4. When assembled in the switch the resilient spring metal blade 56 has a flat Vportion 60 at its inner end and an angular portion 62 extending from the at portion 60 to a point 64 on the switch blade .56. The switch blade 56 A pivoted contact carrying arm is also has a portion 88 that is normally ilat as seen in Figur 4 but assumes a concave form when assemble in the switch which extends longitudinally oi the blade from the point 8l adjacent its inner end to a point 88 adjacent its outer end. The switch blade 88 is provided with the angular portion 88 which extends downwardly from the point 88 and merges into a at portion 10 at the outer end of the switch blade. A movable contact 12 is fastened to the iiat portion 10 of the blade 88 and is receivable in the cut-out portion 38 of the armature 28. The contact 12 engages the stationary contact 88 prior to engagement of the contacts 28 and 52 and the portion 10 of the blade 58 is pressed back from the armature 28 in the switch closed position to provide a predetermined minimum contact pressure.

The concave longitudinal portion A88 of the switch blade 88 engages the armature 28 at substantially a point 18 forming a iulcrum thereon, for the blade 58 The rear portion of the blade 88 is formed with an internal bias and the internal bias in the switch blade 58 exerts a downwardly component force on the armature 28 at the iulcrum point 18. There is also a preformed internal bias in the angular portion 88 of the switch -blade 88 and the component force of the bias ls exerted downwardly at the contact 12.

The bi-asing spring 44 holds the amature 28 and the switch blade 88 in the position shown in Figure 1 when no force or insulcient force is applied to the armature 28 through the resilient arm 38 and -the plunger I8 by an external force and thereby the movable contacts 28 and 12 are maintained out of enagement with the contacts 82 and 80, respectively. There is a Bakelite stop member 18 carried by a bracket 80 which is appropriately secured to the base portion i2 and the stop member 18 limits the upward movement of the switch blade 88 and armature 28.

If the button I8 is gradually depressed, energy will be stored in the resilient arm 88, but the armature 28 will remain in its upper position until the moment -applied thereto by arm 88 overcomes the opposing moment due tothe spring M, at which time the armature will start to move downwardly. As the amature starts to move downwardly it is increasingly attracted by the field of the magnet 41 and is pulled downwardly with a snap action and the contact 12 engages contact 8l) with a snap action. After contact 12 engages contact 50. then contact 29 carried by the amature 28 engages the contact 52. The contact 12 tends to bounce when it engages contact 80 and sets up vibration in the switch blade 88. -The armature 28 will also bounce on engagement of contacts 29-82 but these contacts are not relied on `to make or break the circuit. In order to prevent rapid deterioration of theA contacts it is essential that vibration of the blade 58 and the contact A12 be of extremely short duration. In order -to stop the vibration the energy causing the variation must be dissipated. The front portion of the blade 58 or the 'portion from the fulcrum point 18 to the outer end thereof vibrates when the contact 12 eng-ages the contact 50, and the fulcrum point 18 tends to move slightly towards the secured end of the switch blade 58 'as the portion is pressed back from the armature 28. As the blade 58 vibrates the fulcrum point 18 between the blade 58 and the armature 28 shifts back and forth along the length of the armature. Part of the shifting of this point is due to a rocking effect and part oi' the shifting is frictional sliding. The sliding that takes place between the blade and the armature'dissipates a large part of the vibrating energy. Also the effective spring rate of the outer portion of the blade changes with the shifting of the point I8 and this action appears to aid in stopping the vibration.

It will be noted that the blade 88 is in engagement with the armature 28 at the point 18 when the switch is open as seen in Figure 1. When the contacts are closed andthe portion 18 of blade 88 is pressed back from the armature the blade will still engage the armature intermediate its ends but the point 18 will have shifted slightly away from the contacts. Since 'the normal shape of the blade 58 is as shown in Figure 4, its assembly on the armature 28 as shown in Figure 1 results in suiicient downward bias at the point 18 to maintain that portion of the blade firmly in engagement with the armature in all operative conditions of the switch. Hence, the sliding ac- .tlon that occurs at this point between the blade and armature as the contact 12 moves-with respect to the armature absorbs energy. Vibratory energy of the contact 12 due to impact with the contact 58 is quickly dissipated in friction and arcing between these contacts is thus greatly reduced, increasing the life of the switch and increasing i-ts capacity.

When the external force which is applied to the armature through the plunger I8 and resilient arm 88 decreases due to a change in the condition, the armature 28 will remain in its lower position as determined by engagement of the movable contact 28 engaging stationary contact 82 Vdue to the force of the magnet, but as the force further decreases on the armature 28 the force of the spring 44 will be sumcient that the magnetic force is nally overcome and the armature 28 moves suddenly (due to the non-linear change of the magnetic force) to its open position. moving the contact 12 away from the contact with a snap action.

It will thus be apparent that simple and emcient `means are provided for substantially eliminating bounce of a contact associated with -the switch blade of a snap switch.

While I have herein shown and described a specic embodiment of my invention, I wish it to be understood that modifications may be made without departing from the spirit of the invention, and that I intend therefore to be limited only by the scope of the appended claims.

I claim as my invention: l. In a snap switch, in combination, a stationary contact. a'movable contact arm, a spring blade carrying a movable contact on said arm for exigaing said stationary contact, means for moving said movable contact into engagement with said stationary contact with a snap action, and means independent of said contacts for stopping said arm on movement in a contact closing direction, said spring blade being secured to said arm at one point and formed to bias the remote end theneoi vinto engagement with said arm adjacent said movable contact, and slidably engaging said arm at a third point intermediate the rst and secon points. 2. In a snap switch, in combination, a stationary contact, a movable contact arm, a spring blade carrying a movable contact on said arm for engaging said stationary contact, means for moving said movable contact into engagement with said stationary contact with a snap action. and means independent of said contacts for stopping said arm on movement ina contact closing direction, said spring blade being secured to said arm at one point and formed to bias the remote end thereof into engagement with said arm adjacent said movable contact, and otherwise engaging said arm only at a third point intermediate the lrst and second points, said blade being shaped to cause movement of said third point along' said arm as the remote end of said blade is moved with respect to said arm.

`3. In a snap switch, in combination, a iirst stationary contact, a movable contact arm, a spring blade carrying a rst movable contact on said arm for engaging said first stationary contact, means for moving said first movable contact into engagement with said iirst stationary contact with a snap action, a second movable contact fixed to said arm cooperating with a second stationary contact for stopping said arm on movement in a contact closing direction, said spring blade being secured to said arm at one point and formed to bias the remote end there'of 'into engagement with said arm adjacent saidmovable contact, and slidably engaging said arm at a third point intermediate the first and second points.

.4. In a snap switch, in combination, a stationary contact, a movable contact arm including an armature, a springy blade carrying a movable contact on said arm for engaging said stationary contact, a permanent magnet for moving said movable contact into engagemen-t with said stationary contact with a snap action, and means independent of said contacts ior stopping said 1 arm on movement in a contact closing direction, said spring blade being secured to said arm at one point and formed to bias the remote end thereof into engagement with said arm adjacent.

ary contact,a movable contact arm, a spring blade carrying a movable contact on said arm for engaging said stationary contact, 'means for moving said movable contact into engagement with said stationary contact with a snap action, said spring blade being secured to said arm at one point and formed to bias the remote end thereof into engagement with said arm adjacent said movable contact, and otherwise engaging said arm only at a third p oint intermediate the first and second points, said blade having a bowed portion intermediate the point at which it is secured to said arm and its intermediate point of contact with said arm.

6. In a snap switch, in combination, a stationary contact, a movable contact arm, a spring blade carrying a movable contact on said arm for engaging said stationary contact, means for moving said movablecontact into engagement with said s-tationary contact with a snap action, said spring blade being secured to said arm at one point and formed to bias .the remote end thereof intov engagement with said arm adjacent said movable contact, and frlctionally engaging said arm at a third point intermediate the first and second points.

GEORGE H. BERKHOIDER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Frerer Oct.. 29, 1946 

